mirror of
https://github.com/justinethier/cyclone.git
synced 2025-05-19 05:39:17 +02:00
31 lines
1.3 KiB
Markdown
31 lines
1.3 KiB
Markdown
# Case-Lambda Library
|
||
|
||
The `(scheme case-lambda)` library exports the `case-lambda` syntax.
|
||
|
||
For more information see the [R<sup>7</sup>RS Scheme Specification](../../r7rs.pdf).
|
||
|
||
- [`case-lambda`](#case-lambda)
|
||
|
||
# case-lambda
|
||
|
||
*Syntax*
|
||
|
||
(case-lambda {clause} ...)
|
||
|
||
Syntax: Each `{clause}` is of the form `({formals} {body})`, where `{formals}` and `{body}` have the same syntax as in a lambda expression.
|
||
|
||
Semantics: A `case-lambda` expression evaluates to a procedure that accepts a variable number of arguments and is lexically scoped in the same manner as a procedure resulting from a lambda expression.
|
||
|
||
When the procedure is called, the first `{clause}` for which the arguments agree with `{formals}` is selected, where agreement is specified as for the `{formals}` of a lambda expression. The variables of `{formals}` are bound to fresh locations, the values of the arguments are stored in those locations, the `{body}` is evaluated in the extended environment, and the results of `{body}` are returned as the results of the procedure call.
|
||
|
||
It is an error for the arguments not to agree with the `{formals}` of any `{clause}`.
|
||
|
||
(define range
|
||
(case-lambda
|
||
((e) (range 0 e))
|
||
((b e) (do ((r ’() (cons e r))
|
||
(e (- e 1) (- e 1)))
|
||
((< e b) r)))))
|
||
|
||
(range 3) => (0 1 2)
|
||
(range 3 5) => (3 4)
|